Includes

The purpose of most of the includes in the basic site is building the navigation.

header.html

The include header.html generates the header in the page. It, in turn, “includes” three more includes:

  • title.html
  • navigation.html
  • language-switch.html
<header>
  {% include site-title.html %}
  <nav>
    {% include navigation.html %}

    {% include language-switch.html %}
  </nav>
</header>

The include navigation.html generates an unordered list containing all the published pages having the same language variable as the current page.

<ul>
  {%- assign navigation_pages = site.pages
    | where: 'layout', 'page'
    | where: 'language', page.language
    | where: 'published', true
    | sort: 'order' %}
  {%- for navigation_page in navigation_pages %}
  <li{%- if navigation_page.title == page.title %} class="current"{%- endif %}>
    <a href="{{ site.baseurl }}{{ navigation_page.url }}">{{ navigation_page.title }}</a>
  </li>
  {%- endfor %}
</ul>

In the code above, we create a new variable named navigation_pages which returns a list of the pages that, in their front matter, have:

  • the layout variable set to page
  • the language variable set to the language of the current page (page.language)
  • the published variable set to true

and we order the list according to the order variable. We then loop trough the array of pages and generate the list items of the unordered list.

Whenever the title of the current page in the array (navigation_page.title) matches the title of the current page (page.title), we add a class named current to the corresponding <li/> tag.

language-switch.html

The include language-switch.html generates an unordered list containing all the languages supported in the site. You can use the list to switch to one of the other language translations of the current page/post, if available.

<ul>
  {%- for language in snippets.languages %}

    {%- if page.layout == 'page' %}
      {%- assign navigation_pages = site.pages
        | where: 'language_reference', page.language_reference
        | where: 'language', language[1].slug %}
      {%- if navigation_pages.size == 1 %}
        {%- for navigation_page in navigation_pages %}
          {%- assign url = site.baseurl | append: navigation_page.url %}
        {%- endfor %}
      {%- else %}
        {%- assign navigation_pages = site.pages
          | where: 'language_reference', site.fallback_page
          | where: 'language', language[1].slug %}
        {%- for navigation_page in navigation_pages %}
          {%- assign url = site.baseurl | append: navigation_page.url %}
        {%- endfor %}
      {%- endif %}

    {%- elsif page.layout == 'post' %}
      {%- assign navigation_posts = site.posts
        | where: 'language_reference', page.language_reference
        | where: 'language', language[1].slug %}
      {%- if navigation_posts.size == 1 %}
        {%- for navigation_post in navigation_posts %}
          {%- assign url = site.baseurl | append: navigation_post.url %}
        {%- endfor %}
      {%- else %}
        {%- assign navigation_pages = site.pages
          | where: 'language_reference', site.fallback_page
          | where: 'language', language[1].slug %}
        {%- for navigation_page in navigation_pages %}
          {%- assign url = site.baseurl | append: navigation_page.url %}
        {%- endfor %}
      {%- endif %}

    {%- else %}
      {%- assign navigation_pages = site.pages
        | where: 'language_reference', site.fallback_page
        | where: 'language', language[1].slug %}
      {%- for navigation_page in navigation_pages %}
        {%- assign url = site.baseurl | append: navigation_page.url %}
      {%- endfor %}

    {%- endif %}
    <li{%- if language[1].slug == page.language %} class="current"{%- endif %}>
      <a href="{{ url }}">{{ language[1].value }}</a>
    </li>
  {%- endfor %}
</ul>

In the code above, we loop through the languages defined in the snippets.html file (read the section Snippets for more details).

languages:
  en:
    value: English
    slug: en
  it:
    value: Italian
    slug: it

The for loop contains three different code blocks that are run only if specific conditions are met. If we were to look only at its high-level structure:

<ul>
  {%- for language in snippets.languages %}

    {%- if page.layout == 'page' %}
      <!-- first code block -->

    {%- elsif page.layout == 'post' %}
      <!-- second code block -->

    {%- else %}
      <!-- third code block -->

    {%- endif %}
    <li {%- if language[1].slug == page.language %} class="current"{%- endif %}>
      <a href="{{ url }}">{{ language[1].value }}</a>
    </li>
  {%- endfor %}
</ul>

We run the first block of code only if the layout variable of the current page is set to page, else, if it is set to post, we run the second block of code, else, if it is set to anything else (or to nothing at all), we run the third block of code.

After at least one of the code blocks has been run, we generate the list items of the unordered list.

Whenever the slug of the current language item of the array snippets.languages (language[1].slug) matches the language of the current page (page.language), we add a class named current to the corresponding <li/> tag.

if page.layout == ‘page’

{%- if page.layout == 'page' %}
  {%- assign navigation_pages = site.pages
    | where: 'language_reference', page.language_reference
    | where: 'language', language[1].slug %}
  {%- if navigation_pages.size == 1 %}
    {%- for navigation_page in navigation_pages %}
      {%- assign url = site.baseurl | append: navigation_page.url %}
    {%- endfor %}
  {%- else %}
    {%- assign navigation_pages = site.pages
      | where: 'language_reference', site.fallback_page
      | where: 'language', language[1].slug %}
    {%- for navigation_page in navigation_pages %}
      {%- assign url = site.baseurl | append: navigation_page.url %}
    {%- endfor %}
  {%- endif %}

What does the first block of code do?

{%- assign navigation_pages = site.pages
  | where: 'language_reference', page.language_reference
  | where: 'language', language[1].slug %}

We create a new variable named navigation_pages which returns a list of the pages that, in their front matter, have:

  • the language_reference variable equal to the current page’s language_reference variable (page.language_reference)
  • the language variable equal to the slug of the current language item (language[1].slug) in the array snippets.languages

If we set the front matter of the pages correctly, the size of the array navigation_pages should be:

  • either equal to one if the current page has a corresponding page translated in the current language item of the array snippets.languages
  • or equal to zero if the current page does not have a corresponding page translated in the current language item of the array snippets.languages
{%- if navigation_pages.size == 1 %}
  {%- for navigation_page in navigation_pages %}
    {%- assign url = site.baseurl | append: navigation_page.url %}
  {%- endfor %}

If the size of the array navigation_pages is equal to one, we loop through the array navigation_pages and create a new variable named url by combining the site.baseurl (defined in the _config.yml file) and the url of the one page (navigation_page.url) contained in the array navigation_pages.

{%- else %}
  {%- assign navigation_pages = site.pages
    | where: 'language_reference', site.fallback_page
    | where: 'language', language[1].slug %}
  {%- for navigation_page in navigation_pages %}
    {%- assign url = site.baseurl | append: navigation_page.url %}
  {%- endfor %}
{%- endif %}

If instead, the size of the array navigation_pages is equal to zero (or more than one, which is trouble), we do not have a corresponding page in the current language item of the array snippets.languages to switch to.

Thus, we provide a fallback page (site.fallback_page) so that the web surfers who interact with the language switch and press on a language that does not support the current page are at least redirected to a meaningful page in the language they selected.

We set the fallback_page in the _config.yml file placed in the site’s root directory:

fallback_page: 'stories'

The fallback pages of the basic site are those whose language_reference variable is set to stories.

Why stories? Because—in the context of the basic site—the pages whose language_reference variable is set to stories function as home pages, since they:

  • return a list of all the published posts (they have exactly the same structure as the index.html page)
  • have a translated counterpart in all the languages supported on the site

elsif page.layout == ‘post’

{%- elsif page.layout == 'post' %}
  {%- assign navigation_posts = site.posts
    | where: 'language_reference', page.language_reference
    | where: 'language', language[1].slug %}
  {%- if navigation_posts.size == 1 %}
    {%- for navigation_post in navigation_posts %}
      {%- assign url = site.baseurl | append: navigation_post.url %}
    {%- endfor %}
  {%- else %}
    {%- assign navigation_pages = site.pages
      | where: 'language_reference', site.fallback_page
      | where: 'language', language[1].slug %}
    {%- for navigation_page in navigation_pages %}
      {%- assign url = site.baseurl | append: navigation_page.url %}
    {%- endfor %}
  {%- endif %}

The second block of code behaves akin to the first, with the only difference that we manipulate an array of posts (navigation_posts) rather than one of pages (navigation_pages).

else

{%- else %}
  {%- assign navigation_pages = site.pages
    | where: 'language_reference', site.fallback_page
    | where: 'language', language[1].slug %}
  {%- for navigation_page in navigation_pages %}
    {%- assign url = site.baseurl | append: navigation_page.url %}
  {%- endfor %}

The third block of code runs in the remote eventuality in which both the first and second blocks of code do not run, so that we make sure, again, to serve a fallback page to our web surfers.

Fallback page

How can we be sure that the fallback page truly works?

In this basic site, not all the pages and posts are translated into all the supported languages—on purpose.

English Pages Italian Pages
preface.html prefazione.html
stories.html storie.html
postface.html

If you go to the English page Postface and press on Italian in the language switch, you can see that you are indeed redirected to the Italian page Storie.

English Posts Italian Posts
hello-world.markdown ciao-mondo.markdown
hello-mars.markdown ciao-marte.markdown
ciao-giove.markdown

Similarly, if you go to the Italian post Ciao Giove and press on English in the language switch, you can see that you are indeed redirected to the English page Stories.

title.html

The include title.html generates the title of this basic site.

{%- if page.language == site.default_language %}
  {%- assign url = site.baseurl | append: '/'%}
{%- else %}
  {%- assign navigation_pages = site.pages
    | where: 'language_reference', site.fallback_page
    | where: 'language', page.language %}
  {%- for navigation_page in navigation_pages %}
    {%- assign url = site.baseurl | append: navigation_page.url %}
  {%- endfor %}
{%- endif %}
<h1>
  <a href="{{ url }}" {%- if page.url == '/' %} class="current"{%- endif %}>{{ site.title }}</a>
</h1>

Again, we have two different code blocks that are run only if specific conditions are met.

We run the first code block when the language of the current page (page.language) is equal to the default language (site.default_language) defined in the _config.yml file. Through it we create a new variable named url by combining the site.baseurl (defined in the _config.yml file) and /, that is, the domain name of the site. Web surfers who browse the site in the default language are directed to the main page when they press on the title.

Else, we run the second code block to provide the usual fallback page already discussed above (read the section language-switch.html for more details). Web surfers who browse the site in a language different than the default one are directed to the fallback page in their current language when they press on the title.

localizations.html

The include localizations.html adds <link rel="alternate" … /> tags in the <head/> tag of a page to tell search engines if there are multiple versions of the page for different languages or regions.

{%- if page.layout == 'page' %}
  {%- assign localized_pages = site.pages
    | where: 'language_reference', page.language_reference
    | sort: 'language' %}
  {%- for localized_page in localized_pages %}
    <link rel="alternate" hreflang="{{ localized_page.language }}" href="{{ site.baseurl }}{{ localized_page.url }}" />
  {%- endfor %}

{%- elsif page.layout == 'post' %}
  {%- assign localized_posts = site.posts
  | where: 'language_reference', page.language_reference
  | sort: 'language' %}
  {%- for localized_post in localized_posts %}
    <link rel="alternate" hreflang="{{ localized_post.language }}" href="{{ site.baseurl }}{{ localized_post.url }}" />
  {%- endfor %}

{%- elsif page.layout == 'index' %}
  {%- assign localized_pages = site.pages
    | where: 'language_reference', site.fallback_page
    | sort: 'language' %}
  {%- for localized_page in localized_pages %}
    <link rel="alternate" hreflang="{{ localized_page.language }}" href="{{ site.baseurl }}{{ localized_page.url }}" />
  {%- endfor %}
{%- endif %}

Again, we have three different code blocks that are run only if specific conditions are met (read the section language-switch.html for more details).